Li-rich Mn-based Co-doped Li_1.231Mn_{0.615−0.75x}Ni_0.154Co_xO₂ (x = 0, 0.02, 0.05, 0.07, 0.10, 0.12, 0.15, 0.20, 0.25) cathode materials were prepared by a facile combustion method. X-ray diffraction analysis indicates that the crystal structure of materials has been modified by the doped cobalt ions. The capacity differential results obtained from the galvanostatic charge–discharge process within 2.0 and 4.8 V (vs. Li/Li⁺) indicate that the cobalt doped in the material could conduce to lithium ions re-embedded into the structure and increase the electrical properties. Compared with the electrochemical properties of these materials, the optimum doped sample is Li_1.231Mn_0.525Ni_0.154Co_0.12O₂ (x = 0.12), which delivers an extreme minimum irreversible capacity of 59.1 mA h g⁻¹ with the highest coulombic efficiency of 82.6%, and its discharge specific capacity maintains 180.7 mA h g⁻¹ at 1 C rate after 50 cycles.